Data migration management apparatus and information processing system

ABSTRACT

The present invention provides a data migration management apparatus that can easily create a re-execution task for re-executing an error-terminated data migration task, and also can increase the possibility of the re-execution task being successful. In a case where a data migration from a migration-source volume to a migration-destination volume fails, the management apparatus uses the information of the failed task to create a re-execution task. The management apparatus changes the configuration of a volume pair as necessary. The management apparatus manages the failed task in association with the re-execution task.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application relates to and claims priority from Japanese PatentApplication No. 2009-116486 filed on May 13, 2009, the entire disclosureof which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a data migration management apparatusand an information processing system.

2. Description of the Related Art

The amount of data being handled by companies is increasing every year.For this reason, companies are using a plurality of different storagecontrollers to construct relatively large-scale information processingsystems that manage large volumes of data. Since the frequency withwhich data is utilized will decrease in accordance with the passage oftime, the location where data is stored is reallocated in accordancewith the data utilization frequency.

Accordingly, the effective use of the storage resources inside a dataprocessing system is accomplished by storing data that has a relativelyhigh utilization frequency in a faster logical volume, and migratingdata that has a relatively low utilization frequency to a slower logicalvolume. In the prior art, migration-targeted data is reallocated withinthe information processing system by copying backup data to themigration-destination logical volume.

However, in a method that makes use of backup data, the host computer isprohibited from accessing the migration-targeted data until datareallocation has ended. Therefore, the processing of work on the hostcomputer must stop until data reallocation is over, lowering usability.Accordingly, technology that enables the reallocation of data withoutsuspending host computer access has been proposed (U.S. Pat. No.5,680,640).

In a case where data is migrated while the host computer is permittedaccess as in the prior art disclosed in the above-mentioned patentdocument, host computer access to data and a data copy for migratingthis data are generated simultaneously. This increases the I/O(Input/Output) load of the migration-targeted data.

If host computer access frequency is high in this case, the processingload of the storage controller increases, lengthening the time requiredfor a data copy to be completed. Not only that, but when processing iscarried out giving priority to host computer access, there is also thepossibility of a data copy process ending in error as a result of atimeout error.

When a data migration ends in error, the user managing the informationprocessing system must first specify which data migration, from amongthe plurality of data migrations that were set, has ended in error, andreset a new data migration.

In a relatively large-scale information processing system being used ata company or the like, a plurality of data may be reallocated at onetime at this point. In addition, in a case where a plurality ofdifferent data are mutually associated, these mutually associated datamust be migrated simultaneously.

In a relatively large-scale information processing system like this, acomplicated data migration is planned and executed in the middle of thenight when access is relatively scarce. If the planned data migration isnot completed due to a partial error, the user must once again deviseand reset a complicated data migration plan, lowering usability.

Furthermore, the new data migration plan should be reset in accordancewith the reason for the failure of the initial data migration plan, butsince the user resets the data migration plan relying on his experienceand intuition, there is no guarantee that the new data migration will becompleted as planned.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a datamigration management apparatus and an information processing system thatmake it possible to set and execute a data migration relatively easily.Another object of the present invention is to provide a data migrationmanagement apparatus and an information processing system that make itpossible to estimate the completion time of a data migration based ondata migration history information, and to change the data migrationexecution plans in accordance with the result of this estimation. Yetother objects of the present invention should become clear from thedescriptions of the embodiments explained hereinbelow.

To solve for the above-mentioned problems, a data migration managementapparatus according to a first aspect of the present invention is formanaging a data migration inside an information processing systemcomprising a plurality of storage areas, and has a memory for storing anexecution plan for migrating data from a migration-source storage area,which is included in the storage areas, to a migration-destinationstorage area, which is included in the storage areas; a microprocessorfor creating, managing and executing the execution plan store in thememory; and a communication interface for the microprocessor tocommunicate via a communication network with a storage controller forcontrolling the storage areas, and the microprocessor migrates the datafrom the migration-source storage area to the migration-destinationstorage area by (1) creating the execution plan and storing the plan inthe memory; (2) migrating the data from the migration-source storagearea to the migration-destination storage area by issuing an instructionbased on the execution plan to the storage controller via thecommunication network; (3) determining whether the execution plan wascompleted as planned or failed; (4) using the information included inthe execution plan to create a re-execution plan in a case where theexecution plan is determined to have failed; (5) storing there-execution plan in the memory in association with the execution plan;and (6) issuing a separate instruction based on the re-execution plan tothe storage controller via the communication network.

In a second aspect according to the first aspect, history informationrelated to a data migration executed inside the information processingsystem is also stored in the memory, and the microprocessor estimates amigration completion time required to complete either the execution planor the re-execution plan based on the history information stored in thememory, and outputs the estimated migration completion time inassociation with either the execution plan or the re-execution plan.

In a third aspect according to the second aspect, an execution result ofthe execution plan is reflected in the history information, and themicroprocessor estimates the migration completion time of there-execution plan based on the history information in which theexecution result of the execution plan has been reflected.

In a fourth aspect according to the first aspect, in a case where theexecution plan failed, the microprocessor creates a re-execution plan bychanging either the migration-source storage area or themigration-destination storage area, or both, to a different storage areain accordance with the reason for the failure.

In a fifth aspect according to the fourth aspect, a failure reasontable, which stipulates beforehand whether or not a retry is possiblefor the each failure reason, is stored in the memory, and themicroprocessor determines whether or not the failure reason for theexecution plan is a retryable failure reason by referencing the failurereason table, and in a case where the failure reason for the executionplan is set as being non-retryable, creates a re-execution plan bychanging either the migration-source storage area or themigration-destination storage area, or both, to a different storagearea.

In a sixth aspect according to the fourth aspect, the microprocessorselects the different storage area from among the storage areas based onan attribute of the storage area to be a change target, of themigration-source storage area and the migration-destination storagearea.

In a seventh aspect according to the first aspect, history informationrelated to a data migration executed inside the information processingsystem is also stored in the memory, and in a case where the executionplan failed, the microprocessor determines whether or not it is possibleto re-select the migration-source storage area and themigration-destination storage area included in the execution plan tocreate a re-execution plan, and when the migration-source storage areaand the migration-destination storage area are determined to bere-selectable, the microprocessor estimates, on the basis of the historyinformation, a migration completion time required to complete the datamigration from the migration-source storage area to themigration-destination storage area, and when the estimated migrationcompletion time corresponds to a preset prescribed change condition, themicroprocessor changes the migration-destination storage area to adifferent storage area included in the storage areas.

In an eighth aspect according to the seventh aspect, the microprocessorselects, as the different storage area, a storage area having either thesame or similar attributes as the migration-destination storage areawhich is a change target.

In a ninth aspect according to the seventh aspect, the prescribed changecondition is either one or a plurality of: a case where the migrationcompletion time estimated this time is a first prescribed value orlonger than a previously estimated migration completion time for theexecution plan that failed; a case where the time required from thestart to failure of the execution plan is a second prescribed value orlonger than the previously estimated migration completion time for theexecution plan; and a case where, when a plurality of data migrationpairs configured from the migration-source storage area and themigration-destination storage area are included in the execution plan,the migration completion time estimated for either one of the datamigration pairs is a third prescribed value or longer than the migrationcompletion time estimated for the other data migration pairs.

In a tenth aspect according to the first aspect, a plurality of datamigration pairs configured from the migration-source storage area andthe migration-destination storage area are included in the executionplan, and the microprocessor determines that the execution plan failedin a case where a data migration has failed for either one of the datamigration pairs included in the execution plan, and the microprocessoruses information that is used in setting the data migration pair forwhich data migration failed of the respective data migration pairsincluded in the execution plan that failed, to create a re-executionplan for completing the data migration for the data migration pair forwhich data migration failed.

In an eleventh aspect according to the first aspect, an execution planmanagement table for storing the execution plan and the re-executionplan created by the microprocessor is also stored in the memory, and anidentifier for identifying the execution plan and an identifier foridentifying the re-execution plan are set in the execution planmanagement table so as to differ from one another.

In a twelfth aspect according to the first aspect, in a case where there-execution plan has been associated with the execution plan thatfailed, the microprocessor prohibits the creation of another executionplan related to the execution plan.

An information processing system according to a thirteenth aspect is aninformation processing system comprising a data migration managementapparatus for managing a data migration; and a plurality of storagecontrollers, which are connected to the data migration managementapparatus via a communication network, and which each has a plurality ofstorage areas, wherein the data migration management apparatus has: amemory for storing an execution plan for migrating data from amigration-source storage area, which is included in the storage areas,to a migration-destination storage area, which is included in thestorage areas; a microprocessor for creating, managing and executing theexecution plan stored in the memory; and a communication interface forthe microprocessor to communicate via the communication network with thestorage controllers, and the microprocessor migrates the data from themigration-source storage area to the migration-destination storage areaby (1) creating the execution plan and storing the plan in the memory;(2) migrating the data from the migration-source storage area to themigration-destination storage area by issuing an instruction based onthe execution plan to the storage controllers via the communicationnetwork; (3) determining whether the execution plan was completed asplanned or failed; (4) using the information included in the executionplan to create a re-execution plan in a case where the execution plan isdetermined to have failed; (5) storing the re-execution plan in thememory in association with the execution plan; and (6) issuing aseparate instruction based on the re-execution plan to the storagecontrollers via the communication network.

The present invention may also be perceived as a method for managing adata migration as described below. That is, it is a data migrationmanagement method for managing a data migration inside an informationprocessing system comprising a plurality of storage areas, the datamigration management method comprising the steps of creating anexecution plan for migrating data from a migration-source storage area,which is included in the storage areas, to a migration-destinationstorage area, which is included in the storage areas, and storing samein the memory; migrating the data from the migration-source storage areato the migration-destination storage area by issuing an instruction,which is based on the execution plan, to the storage controller forcontrolling the storage areas; determining whether the execution planwas completed as planned or failed; creating a re-execution plan usingthe information included in the execution plan when the execution planis determined to have failed; storing the re-execution plan in thememory in association with the execution plan; and migrating the datafrom the migration-source storage area to the migration-destinationstorage area by issuing to the storage controller a separate instructionbased on the re-execution plan.

The functions, means or steps of the present invention may be able to beconfigured either entirely or in part as a computer program. Thiscomputer program may be transferred by being affixed on a recordingmedium, or it may also be transmitted via the Internet or other suchcommunication network. Furthermore, the characteristic featuresdescribed above may be combined into combinations other than thosedescribed, and such combination are also included within the scope ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a concept of an embodiment of thepresent invention;

FIG. 2 is a block diagram showing the overall configuration of a system;

FIG. 3 is a diagram schematically showing a data migration;

FIG. 4 is a schematic diagram showing the configuration of a memory of amanagement server;

FIG. 5 is a schematic diagram showing a portion of a task managementtable;

FIG. 6 is a schematic diagram showing the other portion of the taskmanagement table;

FIG. 7 is a schematic diagram of an error information table;

FIG. 8 is a schematic diagram of a volume information table;

FIG. 9 is a schematic diagram of migration history information;

FIG. 10 is a flowchart showing a data migration process in its entirety;

FIG. 11 is a flowchart of a process for creating a data migration task;

FIG. 12 is a flowchart of a process for executing a data migration task;

FIG. 13 is a flowchart of a process for detecting an error occurring ina data migration;

FIG. 14 is a flowchart of a process for instructing are-execution of adata migration;

FIG. 15 is a diagram showing an example of a screen for instructing are-execution;

FIG. 16 is a flowchart of a process for creating a re-execution task;

FIG. 17 is a flowchart of a process for estimating a data migration endtime;

FIG. 18 is a flowchart of a process for creating a volume pair for adata migration;

FIG. 19 is a flowchart of a process for re-selecting amigration-destination volume of the volume pair;

FIG. 20 is a flowchart of a process, which re-selects a volume pair,executed by a system related to a second embodiment;

FIG. 21 is a flowchart of a process, which creates a re-execution task,executed by a system related to a third embodiment;

FIG. 22 is a continuation of the flowchart of FIG. 21; and

FIG. 23 is a flowchart of a process, which creates a data migrationtask, executed by a system related to a fourth embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments of the present invention will be explained hereinbelowwhile referring to the drawings. In this embodiment, setting informationrelated to a data migration task that ended in error is used to create anew task for re-executing this data migration as described hereinbelow.Furthermore, in this embodiment, the time required to end a datamigration is estimated based on data migration history information, andthe result of this estimation is provided to the user. In theexplanation that follows, “data migration” may be shortened to“migration.”

FIG. 1 is a schematic diagram showing an overall concept of thisembodiment. The configuration shown in FIG. 1 is an example for aidingin understanding the present invention, but the scope of the presentinvention is not limited to the configuration shown in FIG. 1. Aninformation processing system, for example, comprises a managementapparatus 1; a plurality of storage apparatuses 2(1), 2(2); a hostcomputer 3 (host computer will be shortened to host hereinafter); andcommunication networks CN1, CN2.

The storage apparatus 2 and host 3 are connected to the managementapparatus 1 via a communication network CN1 for management use. Inaddition, each storage apparatus 2 is connected to the host computer 3and the other storage apparatus 2 via a communication network CN2 forI/O use.

The management communication network CN1, for example, is configurableas a communication network, like either a LAN (Local Area Network) orthe Internet. The I/O communication network CN2, for example, isconfigurable as a communication network, like either a IP-SAN (InternetProtocol-Storage Area Network) or a FC-SAN (Fibre Channel-SAN).Furthermore, the configuration may also be such that I/O data transferand management communications are carried out via a single communicationnetwork instead of using two communication networks CN1, CN2.

The configurations of the storage apparatuses 2(1), 2(2) will beexplained first before explaining the configuration of the managementapparatus 1. The storage apparatuses 2(1), 2(2), which serve as “storagecontrollers”, for example, have controllers 2A and logical volumes 2B.

The respective storage apparatuses 2(1), 2(2) may relate to one anotherequally, or the relation may be such that the one storage apparatus 2(1)uses the storage resources (for example, the logical volume) of theother storage apparatus 2(2). The latter relationship is called an“external connection”, and in accordance with this, the one storageapparatus 2(1) constitutes the connection-source storage apparatus, andthe other storage apparatus 2(2) constitutes the connection-destinationstorage apparatus. In the following explanation, when there is noparticular need to distinguish between the two, the storage apparatuses2(1), 2(2) will be called the storage apparatuses 2.

The controllers 2A control the configurations and operations of thestorage apparatuses 2. The respective logical volumes 2B are logicalstorage areas created on the basis of physical storage areas havingeither one or a plurality of storage devices. More specifically, forexample, physical storage areas each having a plurality of storagedevices are collected into a group, and either one or a plurality oflogical volumes 2B may be set on this group of physical storage areas.In FIG. 1, a number such as “#10”, “#20” and so forth is added foridentifying the respective logical volumes 2B.

As a storage device, for example, various devices capable of reading andwriting data, such as a hard disk device, a semiconductor memory device,an optical disk device, a magneto-optical disk device, a magnetic tapedevice, and a flexible disk device, may be used here.

In a case when a hard disk device is utilized as a storage device, forexample, it is possible to use a FC (Fibre Channel) disk, SCSI (SmallComputer System Interface) disk, SATA disk, ATA (AT Attachment) disk,SAS (Serial Attached SCSI) disk or the like. It is also possible to usea variety of storage devices, such as, for example, a flash memory,FeRAM (Ferroelectric Random Access Memory), MRAM (MagnetoresistiveRandom Access Memory), Ovonic Unified Memory, and RRAM (Resistance RAM).In addition, the configuration may also be such that different types ofstorage devices, such as a flash memory and a hard disk drive, are usedintegratively.

The host 3 is also connected to each of the storage apparatuses 2 viathe communication network CN2, and reads and writes data by accessingthe logical volumes 2B of the respective storage apparatuses 2. The host3, for example, is equipped with application programs, such as customermanagement software and sales management software, and provides servicesto a client computer (not shown in the drawing) connected to the host 3.

The management apparatus 1, for example, comprises a task manager 1A; amigration controller 1B; an error detector 1C; an estimator 1D; and are-execution task creator 1E. These functions 1A through 1E are realizedin accordance with prescribed programs installed in the managementapparatus 1. At least a portion of the respective functions 1A through1E may be configured as a hardware circuit.

The task manager 1A is a function for managing a migration task forre-allocating data. A task for carrying out a migration is inputted,either manually or automatically, into the task manager 1A. The taskmanager 1A manages and stores the progress, scheduled executiondate/time, completion date/time and so forth of each registered task.The task manager 1A also stores the history information related to adata migration task executed in the past.

The migration controller 1B is a function for controlling the executionof a migration task being managed by the task manager 1A. A case wheredata is migrated from the one storage apparatus 2(1) to the otherstorage apparatus 2(2) will be given as an example and explained here.The migration controller 1B issues an instruction to themigration-source storage apparatus 2(1) and/or the migration-destinationstorage apparatus 2(2) on the basis of the migration task, and executesa data migration. The configuration may be such that a data migrationexecution start instruction is only issued to either one of themigration-source storage apparatus 2(1) or the migration-destinationstorage apparatus 2(2). The configuration may also be such that eitheran array group identifier or a storage device identifier is used insteadof specifying the migration-destination volume.

As is described in the embodiments explained hereinbelow, it is possibleto dispose a plurality of volume pairs inside a single migration task.In other words, it is possible to manage and simultaneously migrate aplurality of associated data as a single group. This kind of group iscalled a migration group.

The error detector 1C is a function for detecting an error related tothe data migration process. The error detector 1C, for example, detectsthe occurrence of an error, such as a “timeout”, “communication failure”or “unusable”. The contents of the respective errors will be revealed inthe embodiments explained further below. In a case where a singlemigration task comprises a plurality of data migrations, the errordetector 1C detects the presence or absence of an error for each datamigration. When all the data migrations in a migration task endnormally, it is determined that this migration task ended normally. In acase where any one of the data migrations in the migration task failed,it is determined that this migration task also ended in error.

The re-execution task creator 1E is a function that creates a new taskfor re-executing a data migration that ended in error with respect to amigration task that was not completed due to error. The re-executiontask creator 1E creates a re-execution task using setup information (forexample, the migration-source storage apparatus identifier, themigration-source volume identifier, the migration-destination storageapparatus identifier, and the migration-destination volume identifier)related to the data migration that ended in error.

The re-execution task creator 1E, for example, may have a settingchanger 1E1 and an association unit 1E2. The setting changer 1E1 changesthe configuration with respect to a data migration based on a datamigration error. For example, the setting changer 1E1 selects adifferent logical volume 2B having the same or similar attributes as themigration-destination volume initially selected as a newmigration-destination volume. Consequently, the error that occurred inthe initial migration task is avoided, and the possibility of asuccessful data migration is increased. The association unit 1E2associates the initially created migration task that ended in error witha newly created re-execution task. Consequently, it is possible toeasily discern how much of the initially devised data migration plan wasultimately completed.

As will be described in the embodiments explained further below, there-execution task creator 1E prohibits the creation of a task for are-execution task-including data migration of the data migrations thatended in error. That is, it prohibits a plurality of re-execution tasksfrom being created for a data migration that ended in error.

The estimator 1D estimates the time required for completing a datamigration. The estimator 1D, for example, is able to estimate the timerequired for the completion of a data migration prior to executing thisdata migration based on past history information being managed by thetask manager 1A.

For example, the estimator 1D is able to estimate a data migrationcompletion time by comparing the respective parameters (parameters suchas data size, data transfer rates of migration-source storage device andmigration-destination storage device, and communication line speed) ofthe data migration to be executed from here on out against historyinformation having either the same or similar parameters.

In a case where a plurality of data migrations are included within themigration task, for example, the completion time for this migration taskmay be estimated in accordance with the time of the data migration thatwill be completed the slowest of these data migrations. The above is acase of parallel processing. By contrast, in a case where one datamigration ends before the next data migration is executed, the totalvalue of the times required to complete the respective data migrationsincluded in the one migration task may be utilized as the completiontime of this migration task.

The result of the data migration completion time estimate is madecorrespondent to this data migration, and is managed by the task manager1A. In addition, this estimation result is also provided to the user viaa management screen like that described below using FIG. 15.

A data migration process of this information processing system will beexplained. In the example of FIG. 1, a plurality of logical volumes 2B(#10), 2B (#11) store mutually associated data, and thus belong to thesame migration group.

The user devises a migration plan for this migration group, andregisters this plan in the task manager 1A of the management apparatus1. In this migration plan, one migration-source volume 2B (#10) ismigrated to a migration-destination volume 2B (#20) inside the storageapparatus 2(2), and the other one migration-source volume 2B (#11) ismigrated to the other migration-destination volume 2B (#21) inside thestorage apparatus 2(2). Furthermore, the migration-destination storagearea is not limited to a logical volume 2B, and either an array group(may also be called either a RAID group or a parity group) of a storagedevice may be specified instead.

When the specified time period arrives, the migration controller 1Bissues instructions to the respective storage apparatuses 2(1), 2(2)based on the registered migration task, and migrates data between therespective storage apparatuses 2(1), 2(2). The data migration, forexample, is realized as a data copy between the logical volumes 2B.

Host 3 access is permitted during the data copy as well. It is supposedthat the data copy from the migration-source volume 2B (#10) to themigration-destination volume 2B (#20) was completed normally. However,it is supposed that the data copy from the other migration-source volume2B (#11) to the other migration-destination volume 2B (#21) has failed.

If the host 3 frequently accesses the migration-source volume 2B (#11)during the data copy, the load on the storage apparatus 2(1) withrespect to the migration-source volume 2B (#11) suddenly increases. Forthis reason, many computer resources of the storage apparatus 2(1) areused for processing the commands from the host 3, generating a timeoutduring the data copy process. As a result of this, the data migrationfrom the migration-source volume 2B (#11) to the migration-destinationvolume 2B (#21) ends in an error. The error detector 1C detects thiserror.

The re-execution task creator 1E reuses the information related to thedata migration that ended in error, and creates a new migration task (are-execution task) for re-executing this data migration that ended inerror. Therefore, the user is able to easily create a re-execution taskwithout having to reset all the information required to re-execute thedata migration.

Furthermore, the re-execution task creator 1E has the task manager 1Amanage the re-execution task by associating the initial migration taskwith the re-execution task. Therefore, the user is able to easilydiscern how the initially devised data migration plan was ultimatelyimplemented.

In accordance with configuring this embodiment like this, even in a casewhere a data migration fails, it is possible to easily create a task forre-executing this data migration, enhancing user usability. In addition,the failed migration task is managed in association with the re-executedmigration task making it possible to track where the respective data hasbeen allocated and enabling the user to easily discern the ultimateresult of the data migration execution, thereby enhancing usability.This embodiment will be explained in detail below.

First Embodiment

The first embodiment will be explained based on FIGS. 2 through 19. FIG.2 is a schematic diagram showing the configuration of an overall system.The relationship to the configuration shown in FIG. 1 will be describedfirst. The management server 10 corresponds to the management apparatus1, the storage apparatuses 20(1), 20(2) correspond to the storageapparatuses 2(1), 2(2), the host 30 corresponds to the host 3, thecontrollers 100 correspond to the controllers 2A, and the logicalvolumes 230 corresponds to the logical volumes 2B.

In this embodiment, the management server 10, for example, is connectedto respective hosts 30 via a communication network CN10 such as a LAN.In addition, the management server 10 is connected to the respectivestorage apparatuses 20 via a communication network CN20 such as a SAN.Furthermore, the configurations of the communication networks are notlimited to those shown in FIG. 2.

The management server 10 is for managing the configuration and operationof the system. The management server 10 manages a data migration insidean information processing system. The management server 10, for example,comprises a microprocessor 11; a memory 12; and communication networkinterfaces 13, 14. The microprocessor 11 realizes a data migrationmanagement function, which will be described further below, by readingin and executing a program stored in the memory 12.

The user, for example, is able to access the management server 10 usingeither a personal computer or a handheld terminal equipped with a webbrowser, and may either set a data migration plan or confirm the resultsof data migration execution.

The management server 10, for example, may also have a display device;and an input device such as a keyboard switch and a pointing device. Inaccordance with this, the user may use these input/output devices toinput information to the management server 10, or to have the managementserver 10 output information. Or, as described hereinabove, theconfiguration may be such that a computer for operation and display use,such as a personal computer or handheld terminal, is connected to themanagement server 10, and either a setting is carried out with respectto the data migration or the results of data migration execution aredisplayed via the operation and display computer.

Hereinafter, a cluster of one or more computers, which manage theinformation processing system, set information with respect to a datamigration, and display information related to the data migration may becalled a management system. In a case where a management computer (forexample, the management server 10) comprises the above-mentionedinput/output devices and displays information related to the datamigration, the management computer is the management system. Aconfiguration that combines the management computer with the computerfor operation and display use is also the management system.Furthermore, the configuration may also be such that management isperformed using a plurality of computers for increasing the speed and/orreliability of the management process. In this case, the cluster of thisplurality of computers constitutes the management system.

The respective storage apparatuses 20(1), 20(2) basically may be formedas apparatuses having substantially the same configuration. When thereis no particular need to distinguish between the storage apparatuses20(1), 20(2), they will be called storage apparatuses 20.

This configuration will be explained by giving storage apparatus 20(1)as an example. Storage apparatus 20(1), for example, comprises acontroller 100(1); and a plurality of logical volumes 230(1).

The controller 100(1) controls the operation of the storage apparatus20(1). For example, the controller 100(1) either writes data to atargeted logical volume 230(1) or reads data from the targeted logicalvolume 230(1) in accordance with a command issued from the host 30. Inaddition, the controller 100(1) implements various types of processing(for example, logical volume creation, a data copy between logicalvolumes, and so forth) for a data migration in accordance with aninstruction from the management server 10.

The controller 100(1), for example, comprises a first communication unit110; a second communication unit 120; a microprocessor 130; a cachememory 140; and a data transfer control circuit 150.

The first communication unit 110 is a control circuit for controllingcommunications between the host 30 and the other storage apparatus20(2). The first communication unit 110, for example, is connected tothe host 30 and the other storage apparatus 20(2) via a communicationnetwork CN20 like an IP-SAN or a FC-SAN.

For example, the initiator port of each host 30 is connected to aplurality of target ports of the first communication unit 110, and thetarget port of the other controller 100(2) of the other storageapparatus 20(2) is connected to the initiator port of the firstcommunication unit 110.

The second communication unit 120 is a control circuit for carrying outcommunications with the respective storage devices 210 (Refer to FIG. 3)that configure the respective logical volumes 230(1). The secondcommunication unit 120 is connected to the respective storage devices210 via a plurality of communication paths. Therefore, even if onecommunication path fails, it is possible to access the storage device210 via the other communication path.

The microprocessor (MP in the drawing) 130 is a control circuit forcontrolling the operation of the controller 100(1). The microprocessor130 issues a prescribed instruction based on a command received fromeither the host 30 or the management server 10.

The cache memory (CM in the drawing) 140 is for storing write data andthe like. The area of a portion of the cache memory 140 is used as thecache area, and write data is stored therein. The other area of thecache memory 140 is used as the control information area, and controlinformation and management information are stored therein.

The data transfer control circuit 150 is for interconnecting therespective communication units 110, 120, the microprocessor 130, and thecache memory 140. The other storage apparatus 20(2) also comprises acontroller 100(2) and logical volumes 230(2) the same as the one storageapparatus 20(1).

In this embodiment, the one storage apparatus 20(1) is able toincorporate and use inside the one storage apparatus 20(1) a logicalvolume 230(2) of the other storage apparatus 20(2). This technology iscalled an external connection in this specification. In FIG. 2, twostorage apparatuses 20(1), 20(2) are shown for the sake of expeditingthe explanation, but the scope of the present invention is not limitedto this, and the external connection technology may also be utilized forthree or more storage apparatuses.

Of the respective logical volumes 230(1) of the one storage apparatus20(1), the logical volume 230(1V), to which a “V” has been appended, isa virtual logical volume that has been formed using the logical volume230(2) inside the other storage apparatus 20(2). The logical volume230(1V), in which a real entity is not provided like this, will becalled either an external connection volume or a virtual volume.

The host 30 is able to access the external connection volume 230(1V),but the logical volume in which the data is actually stored is the realvolume 230(2) inside the other storage apparatus 20(2).

Accordingly, the one storage apparatus 20(1) converts a write commandand a read command for the external connection volume 230(1V) to acommand addressed to the connection-destination volume 230(2), and sendsthis converted command to the other storage apparatus 20(2).

By utilizing the external connection technology like this, the onestorage apparatus 20(1) is able to incorporate and use inside the onestorage apparatus 20(1) the logical volume 230(2) from inside the otherstorage apparatus 20(2). In addition, using the functions of the onestorage apparatus 20(1), it is possible to provide data to the host 30from inside the other storage apparatus 20(2), making it possible toenhance the reliability and response performance of the entire system.

The respective hosts 30 provide various services to client computers notshown in the drawing by using the logical volumes 230 inside the storageapparatuses 20. The hosts 30 are connected to the client computers viathe Internet or other such communication network (not shown in thedrawing). Each host 30, for example, comprises a microprocessor 31; amemory 32; and communication network interfaces 33, 34. Themicroprocessor 31 provides the client computer with services such ascustomer management, sales management, and video delivery, for example,by reading in and executing a program stored in the memory 32.

FIG. 3 is a schematic diagram showing an overview of a data migration.In FIG. 3, three storage apparatuses 20(1), 20(2), 20(3) are shown. Thescope of the present invention is not limited to this, and the presentinvention may also be applied to a case where a data migration isexecuted inside a single storage apparatus 20, and is also applicable ina case where a data migration is executed inside a system comprisingfour or more storage apparatuses.

As shown in the upper portion of FIG. 3, physical storage areas, whichhave a plurality of storage devices 210 disposed in the storageapparatus 20(1), are collected together into a single array group220(1), and a logical volume 230(1) is disposed in the storage area ofthis array group 220(1). Similarly, array groups 220(2), 220(3) andlogical volumes 230(2), 230(3) are also disposed in the other storageapparatuses 20(2), 20(3).

A case in which the logical volume 230(1) inside the storage apparatus20(1) is the migration target will be explained. The migrationdestination candidates include array group 220(2) and array group220(3).

The user is able to set a data migration by selecting either of thearray groups 220(2), 220(3). Or, it is also possible for the user to seta data migration by selecting the logical volume 230(2), 230(3)belonging to either of the array groups 220(2), 220(3). In addition, theuser may also set a data migration by selecting a storage device 210belonging to either of the array groups 220(2), 220(3).

FIG. 4 is a diagram schematically showing the storage contents of thememory 12 of the management server 10. A plurality of programs 310through 350 and a plurality of tables T10 through T40 are stored in thememory 12.

As the programs, for example, a task management program 310, an errordetermination program 320, a migration control program 330, a volumeselection program 340, and a migration end time estimation program 350(hereinafter called the estimation program 350) are stored in the memory12. Furthermore, the respective programs 310 through 350 may beinstalled by being sent to the management server 10 from a programdelivery server (not shown in the drawing), or the respective programs310 through 350 may be recorded on recording media and installed bybeing read into the management server 10 from the recording media.

The task management program 310 is a program that manages the task forexecuting a data migration. The error determination program 320 is aprogram that determines whether or not an error has occurred during adata migration process. The migration control program 330 is a programthat issues a prescribed instruction to the respective storageapparatuses 20 involved in a data migration and executes the datamigration. The volume selection program 340 is a program that selectsthe appropriate logical volume when creating a task for re-executing adata migration that ended in an error. The estimation program 350 is aprogram that estimates the time required for the completion of a datamigration.

As the tables, for example, a task management table T10, an errorinformation table T20, a volume information table T30 and migrationhistory information T40 are stored in the memory 12.

Furthermore, in the explanation that follows, the various informationused in the system of this embodiment will be explained usingexpressions such as “table” or “database”. However, names such as“table” and so forth are only used for the sake of convenience, and thevarious information used in this system may also be expressed usingother data structures besides table and database. In other words, thevarious information used in this embodiment is not dependent on a datastructure.

Therefore, for example, the task management table T10 shown in FIG. 4may also be called the task management database, or the task managementlist, or task management information. The same holds true for the othertables T20, T30 as well. Similarly, for example, the migration historyinformation T40 may also be called the migration history managementtable, the migration history management list or the migration historymanagement database. Examples of the configurations of each table T10through T40 will be explained below.

FIG. 5 shows a table T11, which configures a portion of the taskmanagement table T10, and is for managing an overall task. The taskmanagement table T10 has a table T11 used to manage a migration task inits entirety, and a table T12 (refer to FIG. 6) for managing each datamigration of a task. The respective management tables T11, T12 areassociated with each other via a task ID. A plurality of data migrationsmay be registered in a single task. The management table T11 shown inFIG. 5 manages the overall the task, which includes either one or aplurality of data migrations. The management table T12 shown in FIG. 6manages each data migration included inside a single task.

Table T11, which manages a migration task in its entirety, for example,comprises a task ID column C110; a task status column C111; a progresscolumn C112; a start date/time column C113; an end date/time columnC114; an estimated time column C115; a required time column C116; anoriginal task ID column C117; and a re-task ID column C118. What byrights should have been called the “re-execution task ID” has beenshortened to “re-task ID” due to lack of space.

The task ID column C110 manages an identifier (ID) for identifying eachmigration task. The task status column C111 manages the status of eachmigration task. The task status, for example, may include “complete”,“error”, “executing” and “pre-execution (or waiting)”. “Complete”denotes a state in which the data migration was completed normally.“Error” denotes a state in which an error has occurred in either aportion or all of the data migrations included in a task. “Executing”denotes a state in which a data migration is in the process of beingexecuted. “Pre-execution (or waiting)” denotes a state of waiting forthe data migration execution period to arrive.

The progress column C112 manages the state of progress of a migrationtask. The state of progress, for example, expresses in percentage formthe proportion of the size of the data migration that has actually beencompleted with respect to the estimated size of the data migration.

The start date/time column C113 manages the date and time at which adata migration is started. The date/time, for example, may be expressedin the form of a Gregorian Calendar year, month, day, hour, minute andsecond. In the case of a data migration that is in the pre-executionstate, the date/time stored in the start date/time column C113 is thescheduled start date/time. When this data migration is executed, thedate/time stored in the start date/time column C113 becomes thedate/time at which execution was started.

The end date/time column C114 manages the date/time at which a datamigration ended. Either the date/time at which the data migration endednormally, or the date/time at which the data migration ended in error isstored in the end date/time column C114. The end date/time column C114is blank for a data migration that has yet to be executed.

The estimated time column C115 manages the estimated time required tocomplete a data migration. The estimated completion time remains in theestimated time column C115 whether the data migration ends normally orabnormally.

The required time column C116 manages the time actually required for adata migration. In a case where the data migration ends in an error, therequired time column C116 remains blank since the data migration was notcompleted.

The original task ID column C117 manages the ID of the task on which are-execution task was created. The re-task ID column C118 manages the IDfor identifying the re-execution task. In the case of a task that endednormally, the original task ID column C117 and the re-task ID columnC118 remain blank. In the case of a task that has ended in an error, theID of the failed task is stored in the original task ID column C117 ofthe re-execution task when the re-execution task is created for thisfailed task. The ID of the re-execution task is stored in the re-task IDcolumn C118 of the failed task.

In this way, this embodiment assigns a new ID to a new migration task (are-execution task) for executing a failed migration task once again, andmanages this new ID in association with the ID of the original migrationtask (the failed original task). Therefore, it is possible to easilydiscern the relationship between a re-execution task and the originaltask.

FIG. 6 is a schematic diagram showing a table T12 for managing the datamigrations inside respective tasks. This management table T12 isprepared for each task included in the management table T11 shown inFIG. 5.

The management table T12, for example, comprises a task ID column C120,a migration-source volume ID column C121, a migration-destination volumeID column C122, a volume status column C123, a progress column C124, anerror ID column C125, an estimated time column C126, and a required timecolumn C127.

The task ID column C120 manages the ID of the migration task. Themigration-source volume ID column C121 manages the ID of the logicalvolume that is the data migration source. The migration-destinationvolume ID column C122 manages the ID of the logical volume that is thedata migration destination.

The volume status column C123 manages the status of the data migration.Any one of “normal end”, “error termination”, “executing” and“pre-execution (or waiting)” is set in the volume status column C123 asthe state of the migration-source volume. The progress column C124manages the state of progress (the state of progress of the copy) of therespective data migrations.

The error ID column C125 manages an error ID for identifying the causeof an error when a data migration ends in error. The estimated timecolumn C126 manages the estimated time required for a data migration tobe completed. The required time column C127 manages the actual timerequired until a data migration was completed.

FIG. 7 shows an error information table T20. The error information tableT20 manages the types of errors capable of occurring during a datamigration process. The error information table T20, for example,comprises an error ID column C20, an error details column C21, and aretry flag column C22.

The error ID column C20 manages IDs for identifying respective errors.The error details column C21 manages the details of the respectiveerrors. Error details, for example, may include “timeout”, “volume inuse”, “non-migratable volume”, and “communication with external storageapparatus failed”.

The “timeout” is an error that occurs when there is no response within aprescribed period of time from either the migration-source volume or themigration-destination volume during a data migration (that is, during adata copy). The “volume in use”, for example, is an error that occursbecause the host is using the migration-destination volume. The“non-migratable volume”, for example, is an error that occurs when aspecial logical volume like a command device has been selected as themigration-source volume. The “communication with external storageapparatus failed” is an error that occurs when communication with theabove-mentioned external connection-destination storage apparatus fails.

The retry flag column C22 manages a flag that denotes whether or not aretry is possible. In a case where the retry flag has been set to “Yes”,it is possible to re-execute a data migration during which an erroroccurred. In a case where the retry flag has been set to “No”, it is notpossible to execute a data migration during which an error occurred.

For example, when the migration-destination volume is in use, it is notpossible to specify this volume and re-execute the data migration, andthe retry flag is set to “No”. Furthermore, in a case where themigration-source volume is a special logical volume, such as a commanddevice, it is not possible to arbitrarily migrate this special volume.Therefore, the retry flag is set to “No” in this case as well. Also, ina case where a malfunction has occurred on the communication path to theexternal storage apparatus, it is not possible to carry out a datamigration using the external storage apparatus until this malfunctionhas been eliminated. Accordingly, the retry flag is also set to “No” inthis case.

FIG. 8 shows a volume information table T30. The volume informationtable T30 is for managing the respective logical volumes inside theinformation processing system. The volume information table T30, forexample, comprises a volume ID column C30, a RAID level column C31, adisk type column C32, a revolutions column C33, a size column C34, anarray group ID column C35, an apparatus ID column C36, and a connectionpath column C37.

The volume ID column C30 manages IDs for identifying the respectivelogical volumes 230. The RAID level column C31, for example, manages theRAID level and the RAID configuration of a logical volume 230, such as“RAID5 (4D+1p)”, “RAID1 (D+D)”, and “RAID6 (6D+2P)”. The RAID level alsocomprises RAID0.

The disk type column C32 manages the type of storage device 210 thatprovided the storage area to the logical volume 230. For conveniencesake, the storage device is called a “disk”, but the scope of thepresent invention is not limited to a disk shaped recording medium. Thedisk type, for example, may include a SATA disk, a FC disk, or a SSD(solid state device: flash memory device). The revolutions column C33manages the number of revolutions of the storage device 210 thatprovides the storage area to the logical volume 230. Furthermore, in thecase of a flash memory, the data transfer rate may be set instead ofrevolutions.

The size column C34 manages the size of the logical volume 230. Thearray group ID column C35 manages the ID for identifying the array group220 to which the logical volume 230 belongs. The apparatus ID column C36manages the ID for identifying the storage apparatus to which thelogical volume 230 belongs.

The connection path column C37 manages information related to thecommunication path for accessing the logical volume 230. The informationrelated to a communication path for carrying out access, for example,may include WWN (World Wide Name), LUN (Logical Unit Number), iSCSI(internet Small Computer System Interface) name, and IP address. In acase where a plurality of communication paths exist for accessing asingle logical volume, the information related to this plurality ofcommunication paths is recorded in C37.

FIG. 9 shows migration history information T40. The migration historyinformation T40 stores information related to respective data migrationsthat have been carried out in the past. The migration historyinformation T40, for example, may be created based on information fromthe task management table T10 (T11, T12) and the volume informationtable T30.

The migration history information T40, for example, comprises a task IDcolumn C40, a migration-source volume ID column C41, a migration-sourcevolume specifications column C42, a migration-destination volume IDcolumn C43, a migration-destination volume specifications column C44,and a copy speed column C45.

The task ID column C40 manages the ID of a migration task carried out inthe past. The migration-source volume ID column C41 manages the ID ofthe migration-source volume. The migration-source volume specificationscolumn C42 manages information related to the specifications of themigration-source volume. Information related to specifications, forexample, may include the RAID level (to include the RAID configuration),the size, the disk type, and the revolutions.

The migration-destination volume ID column C43 manages the ID of themigration-destination volume. The migration-destination volumespecifications column C44 manages information related to thespecifications of the migration-destination volume. Thespecifications-related information is the same as that described for themigration-source volume. The copy speed column C45 manages the copyingspeed of the data migration carried out in the past.

Furthermore, the configuration may also be such that a migrationinformation column C46 is used instead of the copy speed column C45, andthe data migration start date/time, the copy speed, and the datamigration end date/time are managed inside the migration informationcolumn C46.

In addition, the configuration may also be such that the history ofrespective data migration carried out in the past is managed by the taskmanagement table T10. In this case, the migration history informationT40 is not necessary.

A data migration process will be explained based on FIGS. 10 through 19.The respective flowcharts shown below denote an overview of the process,and the actual computer programs may differ.

The following explanation will focus mainly on the management server 10as the operating entity. In actuality, the prescribed process isrealized in accordance with the microprocessor 11 inside the managementserver 10 reading in and executing a computer program that has beenstored in the memory 12. Therefore, explanation may also be given usingthe microprocessor as the operating entity. Furthermore, based on anunderstanding of the above, the explanation may also be given using thecomputer program as the operating entity.

Furthermore, either all or a portion of the computer programs may alsobe configured from dedicated hardware circuits. The computer programsmay be installed in the management server 10 by way of a programdelivery server for delivering computer programs. Or the computerprograms may be stored on recording media and installed by being readinto the management server 10 from the recording media.

FIG. 10 is a flowchart showing an overview of an entire data migrationprocess. First, the management server 10 creates a task for executing adata migration in accordance with an instruction from the systemadministrator or other such user (S11).

Instead of a user instruction, the configuration may also be such that amigration task is created based on a prepared migration task creationcondition. For example, it is possible to create a migration task in acase where a predetermined condition, such as “migrate data that has notbeen accessed in a predetermined period of time or longer to a lowercost logical volume” has been met.

The management server 10 compares the scheduled start times ofrespective migration tasks registered in the task management table T10against the current time, and when a schedule start time arrives,requests the migration-source storage apparatus and/or themigration-destination storage apparatus to execute a data migration(S12).

This execution request, for example, comprises information forspecifying the migration-source volume and information for specifyingthe migration-destination volume. Furthermore, as described hereinabove,the configuration may also be such that either of amigration-destination array group or a migration-destination storagedevice is specified instead of specifying the migration-destinationvolume. In the explanation that follows, a case in which a logicalvolume is specified as the migration-destination storage device will beexplained.

A data migration (that is, a data copy) from the migration-source volumeto the migration-destination volume is started based on the executionrequest from the management server 10 (S12). A response such as thatdescribed below is possible in a case where the host 30 accesses themigration-source volume during the data copy. Furthermore, to beprecise, writing data to the migration-source volume signifies writingdata to the storage device 210 corresponding to the migration-sourcevolume, but for the sake of convenience, will be expressed as “writesdata to the migration-source volume”. Also, reading data from themigration-source volume actually signifies either reading data from thestorage device 210 corresponding to the migration-source volume orreading data from the cache area corresponding to the migration-sourcevolume. However, for convenience sake, this will be expressed as “readsdata from the migration-source volume”. The same holds true for thereading and writing of data from/to the migration-destination volume.

(1) Permit a read access for reading data from the migration-sourcevolume;

(2) In the case of a write access for updating data inside themigration-source volume, if the write-destination (update-destination)area is a copied area, which has already been copied to themigration-destination volume, write the new data to both themigration-source volume and the migration-destination volume, and returna completed-response to the host 30 after this write has been completed;

(3) Or, in a case that corresponds to a copied area, write the new datato the migration-source volume before returning the write-completeresponse to the host 30. Thereafter, copy new data from themigration-source volume to the migration-destination volume as arepeatedly executed copy process (called the update copy). In a methodlike this, it is possible to shorten the time for processing the writerequest. However, in a case where there is a large amount of write dataper unit of time (particularly, a case in which the write request to themigration-source volume is repeated frequently), due to there beinglimits on the amount of data capable of being processed in an updatecopy, it may not always be possible to estimate the time until datamigration completion.

Furthermore, the method for processing an access from the host 30 duringa data migration is not limited to the method described above. However,when there are numerous accesses from the host 30 during a datamigration, data migration processing speed decreases, and there is apossibility of ending in an error due to a timeout.

When an error occurs in a data migration process, the management server10 detects this error (S13). The controller 100 of each storageapparatus 20 monitors the status of each storage device 210, and in acase where a malfunction of some sort has occurred, such as a diskmalfunction or a controller malfunction, notifies the management server10 of the information related to this malfunction.

The malfunction-related information, for example, may comprise anidentifier for specifying the storage device 210 and/or the array group220 in which the malfunction occurred, an identifier for specifying thelogical volume 230 in which the malfunction occurred, and a codedenoting the type of malfunction.

Furthermore, instead of a configuration in which the occurrence of amalfunction is notified to the management server 10 from the controller100, the configuration may be such that the management server 10, eitherregularly or irregularly, queries the controller 100 as to the presenceor absence of a malfunction.

The controller 100, upon detecting a malfunction, cancels the datamigration process related to this malfunction. The controller 100notifies the management server 10 to the effect that the data migrationprocess has been cancelled. The configuration may also be such thatinformation denoting that the malfunction was either a disk malfunctionor a controller malfunction is sent to the management server 10 from thecontroller 100 at the time of this notification.

As described hereinabove, when an error is detected during the datamigration process, this data migration process is cancelled. The user,based on a screen provided from the management server 10 (refer to FIG.15) is able to request the creation of a task for re-executing themigration task that ended in error (S14).

The management server 10 creates a re-execution task based on therequest from the user, and registers this re-execution task in the taskmanagement table T10 (S15). Furthermore, instead of a configuration thatcreates a re-execution task in accordance with a user instruction, theconfiguration may be such that the re-execution task is created when apreset condition has been met.

The management server 10, upon the arrival of the start date/time thathas been set for the re-execution task, requests that themigration-source storage apparatus and/or the migration-destinationstorage apparatus execute the data migration process (S16). Each processwill be explained in more detail below by referring to the drawings.

FIG. 11 is a flowchart showing the process for creating a data migrationtask. This process corresponds to S11 of FIG. 10.

The management server 10, for example, respectively selects themigration-source volume and the migration-destination volume based onthe instruction from the user (S20, S21), and also sets the datamigration start date/time (S22). The configuration may also be such thatthe selection of the migration-source volume and themigration-destination volume, and the setting of the start date/time arecarried out either automatically or semi-automatically.

The management server 10 estimates the time required for the completionof the data migration set in S20 through S22 (S23). The process forestimating the data migration completion time will be described furtherbelow using FIG. 17.

The management server 10 registers the data migration set in S20 throughS22 and the completion time estimated in S23 in the task managementtable T10 (S24). The management server 10 repeats S20 through S24 untilit determines that the creation of the migration tasks has beencompleted (S25). When the creation of the migration task has beencompleted (S25: YES), this process ends.

FIG. 12 is a flowchart showing the process for executing a datamigration task. The process shown in FIG. 12 corresponds to S12 of FIG.10. The management server 10 references the task management table T10(S30), and determines whether or not a task exists for which theexecution timing (scheduled start date/time) has arrived (S31).

In a case where a task for which the execution timing has arrived isdiscovered (S31: YES), the management server 10 respectively extractsthe identifier specifying the migration-source volume and the identifierspecifying the migration-destination volume included in this task (S32).

The management server 10, based on the extracted information, instructsthe migration-source storage apparatus and/or the migration-destinationstorage apparatus to execute the data migration (S33). A plurality ofdata migrations may be included in a single task. This is due to theneed to migrate in unison a plurality of logical volumes managed by asingle migration group.

Therefore, a data migration is started for each volume pair. A volumepair may also be called a copy pair. The data migrations between therespective volume pairs may be processed parallelly. Or, theconfiguration may be such that after the data migration of one volumepair has been completed, the data migration of the next volume pair isstarted.

When one data migration is complete, a report is made to the managementserver 10 from at least one of either the migration-source storageapparatus or the migration-destination storage apparatus to the effectthat the data migration process has been completed (S34). Data migrationis carried out for each volume pair. Therefore, the storage apparatusreports to the management server 10 to the effect that data migrationhas been completed for each volume pair.

The management server 10, upon receiving the report from the storageapparatus, updates the task management table T10 (in particular, tableT12) (S35), and determines whether or not all the data migrations withinthe task have been completed (S36).

In a case where an unfinished data migration remains within this task(S36: NO), the management server 10 returns to S30 and waits for acomplete-report from the storage apparatus. Further, when the executiontiming of another task arrives, the management server 10 instructs thestorage apparatus to execute this other task. That is, the managementserver 10 is able to process a plurality of migration tasks in parallel.

When all the data migrations within a single task have ended (S36: YES),the management server 10 updates the task management table T10 (inparticular, table T11) (S37), and ends this process. Furthermore, errortermination is also determined to be the end of a data migration.

FIG. 13 is a flowchart showing a process for detecting an error. Thisprocess corresponds to S13 of FIG. 10. The management server 10determines whether or not the data migration ended in error based on thenotification from the storage apparatus 20 (S40). In a case where thedetermination is that the data migration ended in an error (S40: YES),the management server 10 references the error information table T20,specifies the error ID (S41), and stores the error ID in the taskmanagement table T10 (table T12 in particular) (S42).

FIG. 14 is a flowchart showing the process for instructing themanagement server 10 to re-execute a failed migration task. This processcorresponds to S14 of FIG. 10. This process will be explained here byreferring to the screen of FIG. 15.

FIG. 15 shows a task management screen G10 provided by the managementserver 10. The task management screen G10 is created based on the taskmanagement table T10. The user is able to display the task managementscreen G10 whenever necessary to check the execution status of therespective tasks.

The task management screen G10, for example, comprises a check columnG100, a task ID column G101, a task type column G102, a task statuscolumn G103, a progress column G104, a start date/time column G105, anend date/time column G106, an estimated time column G107, an executebutton G108, a cancel button G109, a pause button G110, and a re-executebutton G111.

The check column G100 is used to select a task. The Task ID column G101displays the ID of each task. The task type column G102 displays thetype of each task. Since a data migration is being described, in thisembodiment the task type is “migration”. Furthermore, another task type,for example, may be a shredder task that carries out a shredder task fordestroying data.

The task status column G103 displays the status of a task. Taskstatuses, for example, may include “complete”, “error”, “executing” and“pre-execution”. The progress column G104 displays the state of progressof a task in the form of a percentage. The start date/time column G105displays either the date/time at which a task started, or the date/timeat which the start was scheduled. The end date/time column G106 displaysthe date/time of either the normal-end or error-termination of a task.The estimated time column G107 displays the estimated time required tocomplete a task.

The execute button G108 is for executing a selected task. The cancelbutton G109 is for cancelling a selected task. The pause button G110 isfor temporarily suspending the execution of a selected task. There-execute button G111 is for creating a re-execution task for aselected task.

Return to FIG. 14. The management server 10 determines whether or not atask that ended in an error has been selected by the user in the taskmanagement screen G10 (S50). Then, the management server 10 determineswhether or not the re-execute button G111 has been operated for theerror-terminated task (S51). In a case where the re-execute button G111has been operated (S51: YES), the management server 10 boots up theprocess for creating the re-execution task (S52).

FIG. 16 is a flowchart showing the process for creating a re-executiontask. The management server 10 references the task management table T10(S60), and determines whether or not there is a task that ended in anerror (S61). When an error-terminated task exists (S61: YES), themanagement server 10 determines whether or not this error-terminatedtask is a re-execute task (S62). That is, a determination is made as towhether or not it is a task that has failed two times in a row (S62).

In a case where either not one error-terminated task exists (S61: NO),or the error-terminated task is a re-execution task (S62: YES), an errorprocess is carried out (S66). The management server 10, for example,notifies the user of an error message such as “no re-executable tasks”.

In a case where a task other than a re-execution task ended in an error(S61: YES and S62: NO), the management server 10 extracts the volumepair of the error-terminated data migration from the error-terminatedtask, and creates a volume pair for executing the data migration onceagain (S63). A detailed explanation will be given further below, but ina case where the volume pair of the error-terminated data migration isable to be used as-is, this volume pair is used as-is to create a datamigration for re-execution. In a case where the volume pair of theerror-terminated data migration is unable to be used as-is, for example,a different migration-destination volume is selected and a new volumepair is created.

The management server 10 estimates the data migration completion timefor the re-execution, and stores the contents set in S63 and theestimated completion time in the task management table T10 (S64). S63and S64 are repeatedly executed until preparations for the re-executionof the error-terminated data migration within the error-terminated taskare complete (S65).

FIG. 17 is a flowchart of the process for estimating the migrationcompletion time (migration end time). This process is used in S23 ofFIG. 11 and S64 of FIG. 16.

The management server 10 respectively acquires information related tothe migration-source volume and information related to themigration-destination volume form the volume information table T30 (S70,S71). The volume-related information, for example, may include the RAIDlevel (including the RAID configuration), the disk type, therevolutions, the size, and the apparatus ID.

The management server 10 retrieves the migration history information T40based on the information acquired in S70 and S71 (S72), and determineswhether or not there is a data migration history with a matching volumepair configuration (S73). That is, the management server 10 searches thehistory of data migrations carried out in the past for a volume pairthat has the same configuration as the volume pair for which anestimation of the data migration completion time is to be made.

In a case where a data migration having the same configuration as theestimation-targeted volume pair has not been carried out in the past(S73: NO), the management server 10 references the table T50 formanaging the standard copy speed, and selects a prepared standard copyspeed (S74).

The standard copy speed, for example, may be stipulated based on theaverage value of the measured speed of a data migration carried out inthe past. A plurality of standard copy speeds, for example, may beprepared in accordance with the conditions, such as by RAID level, disktype or revolutions. In accordance with this, the management server 10may also use a plurality of standard copy speeds in accordance with therespective conditions to compute a copy speed for use in making anestimate.

In a case where a data migration having the same configuration has beencarried out in the past (S73: YES), the management server 10 selects thecopy speed at the time of the past data migration (S75). The managementserver 10 estimates the time required to complete the data migrationbased on the copy speed selected in either S74 or S75 (S76). Simplystated, the management server 10 is able to estimate the completion timeby dividing the data migration size by the copy speed (estimatedcompletion time=size of data migration/copy speed).

Furthermore, when estimating the completion time for a re-executiontask, the latest migration history information T40 is used. That is, themanagement server 10 estimates the completion time of the re-executiontask using the latest migration history information T40 (new) ratherthan the migration history information T40 (old) used to estimate thecompletion time for the failed original task. Consequently, it ispossible to enhance estimation accuracy.

Furthermore, the re-execution task completion time is estimated based onthe completion times for the respective data migrations included in there-execution task, and the completion time for the successful datamigration in the original failed task is not taken into account.

For example, it is supposed that the initial task is the first task, andthat a first pair comprising volume #10 and volume #20, a second paircomprising volume #11 and volume #21, and a third pair comprising volume#12 and volume #22 are included within the first task.

It is supposed that the result of executing the first task was that onlythe data migration of the first pair of volume #10 and volume #20 wassuccessful, and the data migrations of the second pair (the pair ofvolume #11 and volume #21) and the third pair (the pair of volume #12and volume #22) failed.

Accordingly, a second task is created as a re-execution task. The secondtask comprises the second pair and the third pair. The management server10 respectively estimates the completion time of the second pair datamigration and the completion time of the third pair data migration basedon the latest migration history information T40 (new) updated subsequentto the end of the first task. In addition, the management server 10estimated the completion time of the second task based on the secondpair completion time and the third pair completion time.

FIG. 18 is a flowchart showing the process for creating a volume pairfor re-executing a data migration. This process corresponds to S63 ofFIG. 16.

The management server 10 extracts the volume pair for theerror-terminated data migration (S80), and references the errorinformation table T20 to confirm the error related to this volume pair(S81).

The management server 10 determines whether or not the error thatoccurred with respect to the volume pair is a retryable error (S82). Inthe case of a retryable error (S82: YES), the management server 10re-selects the original migration-source volume andmigration-destination volume and creates a volume pair (S83). That is,in the case of a retryable error, the volume pair configuration does notchange.

By contrast, in a case where the error that occurred in the volume pairis not a retryable error (S82: NO), the management server 10, as will bedescribed below, changes and re-selects the volume pair configuration(S84).

FIG. 19 is a flowchart showing the process for re-selecting the volumepair. This process corresponds to S84 of FIG. 18. The management server10 determines whether or not the error determined to be a non-retryableerror is an error related to the migration-destination volume (S90).

In a case where the error is related to the migration-destination volume(S90: YES), the management server 10 retrieves, from among the pluralityof logical volumes of the migration-destination storage apparatus, adifferent logical volume having the same attributes as the originalmigration-destination volume (S91). For example, in a case where theinitially selected migration-destination volume comprises attributessuch as “RAID5 (3D+1P), SATA disk, 7200 rpm”, the management server 10retrieves a different logical volume having the same attributes as theoriginal attributes.

When a logical volume, which has the same attributes as the initiallyselected migration-destination volume, and which is capable of becominga candidate (may be called the candidate volume), is detected (S92:YES), the management server 10 selects the detected candidate volume asthe new migration-destination volume, and resets the volume pair (S93).

In a case where either the error was in the migration-source volume(S90: NO), or a candidate volume is not found (S92: NO), the errorprocess is carried out (S94). The management server 10, for example,notifies the user of an error message such as “Unable to select volumepair for re-execution of data migration”.

Configuring this embodiment like this achieves the following effects. Inthis embodiment, when a task comprising a plurality of data migrationshas failed, the user is able to instruct the creation of a re-executiontask using the management screen G10 as shown in FIG. 15. Consequently,it is possible to create a re-execution task using the information ofthe failed task, enhancing usability.

In this embodiment, management is carried out by associating the failedoriginal task with the re-execution task as shown in the managementtable T11 of FIG. 5. Therefore, it is possible to readily confirm thefinal result of a data migration, enhancing usability.

In this embodiment, a new task ID is assigned to the re-execution taskand made correspondent to the original task ID. Consequently, it ispossible to uniformly manage in accordance with the task managementtable T10 the logs of the respective data migrations carried out insidethe information processing system. That is, in this embodiment, themigration history information T40 may be omitted. However, forconvenience sake, this embodiment was explained by giving aconfiguration that utilizes migration history information T40 as anexample.

In this embodiment, in the case of a retryable error, the volume pair ofthe failed data migration is re-selected, and in the case of anon-retryable error, a different logical volume having the sameattributes as the original migration-destination volume is selected anewand a data migration is set. Therefore, it is possible to increase thepossibility of the re-execution task ending normally.

In this embodiment, the time required to complete a data migration isestimated, and the result of this estimation is provided to the user(Refer to FIG. 15). Therefore, the user is able to know beforehand abouthow long the data migration will take, enhancing usability. For example,the user is able to instruct or transpose the execution order of aplurality of tasks such that the migration task having the longestcompletion time is started first.

Second Embodiment

A second embodiment will be explained based on FIG. 20. The followingembodiments, to include this embodiment, are equivalent to variations ofthe first embodiment. Therefore, in the embodiments that follow, theexplanations will focus on the differences with the first embodiment. Inthe second embodiment, when a candidate volume is retrieved, a logicalvolume, whose important attributes match those of the initially selectedmigration-destination volume, is retrieved.

FIG. 20 is a flowchart showing a volume pair re-selection process thatis implemented by the management server 10 according to this embodiment.This process comprises S90 and S92 through S94 in common with theprocess shown in FIG. 19; only S91A differs.

In the case of a migration-destination volume error (S90: YES), themanagement server 10 references a table T60 for managing attributes inorder of priority, and retrieves a candidate volume whose highestpriority attribute matches the highest priority attribute set beforehand(S91A).

The priority of each attribute, such as the RAID level, the disk type,the revolutions, and the array group ID, is set beforehand in theattribute priority management table T60. Attributes for which the orderof priority is set relatively high, for example, may include the RAIDlevel and the disk type. Attributes for which the order of priority isset relatively low, for example, may include the array group ID andrevolutions.

The management server 10 selects as the candidate volume, from among theplurality of logical volumes capable of being selected as themigration-destination volume, the logical volume whose high priorityattribute matches that of the initially selected migration-destinationvolume.

Configuring this embodiment like this achieves the same effects as thoseof the first embodiment. Furthermore, in this embodiment, the logicalvolume whose high priority attribute matches that of the initiallyselected migration-destination volume is retrieved as the candidatevolume that will replace the initially selected migration-destinationvolume. Therefore, it is possible to broaden the range of the volumescapable of being selected as the candidate volume, enhancing usability.

Third Embodiment

A third embodiment will be explained based on FIGS. 21 and 22. In thisembodiment, in a case where a retryable error has occurred in a datamigration, the volume pair configuration is changed based on anestimation result for the data migration completion time. FIG. 21 is aflowchart showing the re-execution task creation process implemented bythe management server 10 of this embodiment.

The management server 10 determines whether or not there is a task thatended in an error (S100). When an error-terminated task exists (S100:YES), the management server 10 determines whether or not thiserror-terminated task is a re-execution task (S101).

In a case where either no error-terminated task exists (S100: NO) or theerror-terminated task is a re-execution task (S101: YES), the managementserver 10 proceeds to the error process shown in FIG. 22 (S111). In theerror process, for example, a prepared error message is notified to theuser.

Return to FIG. 21. In a case where the error-terminated task is not are-execution task (S101: NO), the management server 10 extracts thevolume pair for which data migration failed within this error-terminatedtask (S102).

The management server 10 determines whether or not the cause of thisdata migration error is retryable (S103). If it is not a retryable error(S103: NO), the management server 10 executes the process explainedusing either FIG. 19 or FIG. 20 (S104).

If it is a retryable error (S103: YES), the management server 10re-estimates the time required to complete the data migration for theinitially selected volume pair (S105).

In the first embodiment, in the case of a retryable error, the datamigration is executed once again using the initially selected volumepair (the original volume pair). By contrast, in this embodiment, thecompletion time is re-estimated, and the volume pair configuration ischanged in accordance with the result thereof. Accordingly, in thisembodiment, the data migration completion time for the initial volumepair is re-estimated (S105).

The management server 10 determines whether or not the volume paircorresponds to the configuration change condition on the basis of theestimated completion time. The conditions for changing the configurationof the volume pair, for example, are defined beforehand as describedbelow.

(Condition 1) When the completion time T_(new) estimated this time isα-times or greater than the completion time T_(old) estimated previously(T_(new)≧T_(old)×α, where α>0). For example, the value of αmay be set ataround “1.2”. The value of α is an example, and the scope of the presentinvention is not limited to this value. The same holds true for β and γdescribed hereinbelow.

(Condition 2) When the error-termination time T_(error) of the originaltask is β-times or greater than the completion time T_(new) estimatedthis time (T_(error)≧T_(new)×β, where β>0). For example, the value of βmay be set at around “2”.

(Condition 3) When there is a volume that has a completion timeT_(vol2)of γ-times or greater than the completion time T_(vol1) ofanother volume pair (T_(vol2)≧T_(vol1)×γ, where γ>0). For example, thevalue of γ may be set at around “1.5”.

The above-mentioned conditions 1 through 3 are examples, and the scopeof the present invention is not limited thereto. A determination mayalso be made as to whether or not a volume pair configuration should bechanged based on another condition.

In a case where the volume pair does not correspond to a configurationchange condition (S106: NO), the management server 10 sets the originalvolume pair as the new volume pair (S107), and proceeds to S115 of FIG.22.

In a case where the volume pair corresponds to a configuration changecondition (S106: YES), the management server 10 determines whether ornot it was a migration-destination volume error (S108). In a case wherethe error is not in the migration-destination volume (S108: NO), theerror process is carried out, and a prescribed error message is notifiedto the user (S111).

In a case where the error is in the migration-destination volume (S108:YES), the management server 10 proceeds to S109 of FIG. 22. Refer toFIG. 22. The management server 10 retrieves a candidate volume havingthe same attributes as the original migration-destination volume insidethe migration-destination storage apparatus (S109). As was explained inthe second embodiment, the configuration may be such that the highestpriority attribute of the candidate volume matches that set in theoriginal migration-destination volume.

The management server 10 determines whether or not a candidate volumewas found (S110). In a case where not one candidate volume could befound (S110: NO), the error process is carried out, and a prescribederror message is notified to the user (S111).

In a case where a candidate volume was found (S110: YES), the managementserver 10 estimates the data migration completion time for the candidatevolume (S112). The management server 10 determines whether thecompletion time estimated for the candidate volume fails to correspondto the condition for changing the volume pair configuration describedhereinabove (S113). In a case where, if selected, this candidate volumewill correspond to the volume pair configuration change condition (S113:NO), the management server 10 returns to S109 and retrieves a differentcandidate volume.

In a case where the candidate volume does not correspond to the volumepair configuration change condition (S113: YES), the management server10 resets the volume pair using this candidate volume (S114), andregisters the re-execution task in the task management table T10 (S115).

The management server 10 determines whether or not a re-execution taskhas been created for each error-terminated task for which the creationof a re-execution task was instructed (S116). In a case where thereremains an error-terminated task for which a re-execution task has notbeen created (S116: NO), the management server 10 returns to S102. Whenre-execution tasks have been created for all the instructederror-terminated tasks (S116: YES), this process ends.

Configuring this embodiment like this also achieves the same effects asthe first embodiment and the second embodiment. In addition, in thisembodiment, a determination is made as to whether or not it is better tochange the configuration of the volume pair based on the data migrationcompletion time even in a case where the original volume pair is able tobe re-selected as-is. Therefore, it is possible to further increase thepossibility that the re-execution task will be successful, enabling theenhancement of user usability and system reliability.

Fourth Embodiment

A fourth embodiment will be explained based on FIG. 23. In thisembodiment, the determination as to whether or not the volume paircorresponds to the configuration change condition described in the thirdembodiment is made when creating a data migration task.

FIG. 23 is a flowchart of the process for creating a data migration taskexecuted by the management server 10 in accordance with this embodiment.This process comprises all of S20 through S25 shown in FIG. 11.Furthermore, in this process, the new steps S26 and S27 are addedbetween S23 and S24.

The management server 10, subsequent to estimating the data migrationcompletion time for the created volume pair (S23), makes a determinationas to whether or not this estimated time corresponds to the volume pairconfiguration change condition (S26).

In a case where the estimated time does correspond to the volume pairconfiguration change condition (S26: YES), the management server 10changes the configuration of the volume pair by carrying out the processshown in either FIG. 19 or FIG. 20 (S27).

Configuring this embodiment like this also achieves the same effects asthe first through the third embodiments. Furthermore, in thisembodiment, the determination as to whether or not the configuration ofthe volume pair is appropriate based on the estimation value of the datamigration completion time is made beforehand at the point in time thatthe task is created. Therefore, it is possible to increase thepossibility that the data migration task will be successful, enhancingusability and reliability.

Furthermore, the present invention is not limited to the respectiveembodiments described hereinabove. A person having ordinary skill in theart should be able to make various additions and changes withoutdeparting from the scope of the present invention. For example, it isalso possible to arbitrarily combine the respective embodimentsdescribed above. For example, with the exception of the configurationfor estimating the migration completion time, it is possible to combinethe above-mentioned embodiments with respect to migration taskre-creation and related aspects. By contrast, with the exception of theconfiguration for re-creating the migration task, it is also possible tocombine the above-mentioned embodiments with respect to the estimatedmigration completion time and related aspects. These combinations arealso included within the scope of the present invention.

In the above-mentioned embodiments, cases that omit the preservation ofdata in the migration-destination volume were explained. However, amethod for carrying out a data migration while preserving the data ofthe migration-destination volume by transposing the data of themigration-destination volume and the data of the migration-source volumeis known. In the case of the transposition method, for example, a savevolume for temporary use is prepared, data is migrated from themigration-destination volume to the save volume, then data is migratedfrom the migration-source volume to the migration-destination volume,and finally the data is migrated from the save volume to themigration-source volume. The transposition method may also be realizedvia a method other than the three steps mentioned above.

Furthermore, in a case that omits the preservation of the data of themigration-destination volume as described in the above-mentionedembodiments, there is the possibility of another user, who differs fromthe user that created the migration task, migrating different data tothe migration-destination volume beforehand. In this case, the datamigration to this migration-destination volume may be inhibited toprevent the data that had been moved to the migration-destination volumefrom being overwritten.

This inhibiting process may be carried out by either the storageapparatus side or the management server side. This inhibiting process,for example, may be realized by making it possible to respectively setinformation as to whether this migration-destination volume is able tobe set as the migration destination in each volume. If settabilityinformation like this is prepared, it is possible to prevent data frombeing copied from various different migration-source volumes to the samemigration-destination volume.

1. A data migration management apparatus for managing a data migrationinside a data processing system that comprises a plurality of storageareas, comprising: a memory storing an execution plan for migrating datafrom a migration-source storage area, which is included in the storageareas, to a migration-destination storage area, which is included in thestorage areas; a microprocessor creating, managing and executing theexecution plan stored in the memory; and a communication interface forthe microprocessor to communicate via a communication network with astorage controller for controlling the storage areas, wherein themicroprocessor migrates the data from the migration-source storage areato the migration-destination storage area by: (1) creating the executionplan and storing the plan in the memory; (2) migrating the data from themigration-source storage area to the migration-destination storage areaby issuing an instruction based on the execution plan to the storagecontroller via the communication network; (3) determining whether theexecution plan was completed as planned or failed; (4) using theinformation included in the execution plan to create a re-execution planin a case where the execution plan is determined to have failed; (5)storing the re-execution plan in the memory in association with theexecution plan; and (6) issuing a separate instruction based on there-execution plan to the storage controller via the communicationnetwork.
 2. The data migration management apparatus according to claim1, wherein history information related to a data migration executedinside the information processing system is also stored in the memory,and wherein the microprocessor estimates a migration completion timerequired to complete either the execution plan or the re-execution planbased on the history information stored in the memory, and outputs theestimated migration completion time in association with either theexecution plan or the re-execution plan.
 3. The data migrationmanagement apparatus according to claim 2, wherein an execution resultof the execution plan is reflected in the history information, andwherein the microprocessor estimates the migration completion time ofthe re-execution plan based on the history information in which theexecution result of the execution plan has been reflected.
 4. The datamigration management apparatus according to claim 1, wherein in a casewhere the execution plan failed, the microprocessor creates there-execution plan by changing either the migration-source storage areaor the migration-destination storage area, or both, to a differentstorage area in accordance with the reason for the failure.
 5. The datamigration management apparatus according to claim 4, wherein a failurereason table, which stipulates beforehand whether or not a retry ispossible for the each failure reason, is stored in the memory, andwherein the microprocessor determines whether or not the failure reasonfor the execution plan is a retryable failure reason by referencing thefailure reason table, and in a case where the failure reason for theexecution plan is set as being non-retryable, creates the re-executionplan by changing either the migration-source storage area or themigration-destination storage area, or both, to the different storagearea.
 6. The data migration management apparatus according to claim 4,wherein the microprocessor selects the different storage area from amongthe storage areas based on an attribute of the storage area to be achange target, of the migration-source storage area and themigration-destination storage area.
 7. The data migration managementapparatus according to claim 1, wherein history information related to adata migration executed inside the information processing system is alsostored in the memory, and wherein, in a case where the execution planfailed, the microprocessor determines whether or not it is possible tore-select the migration-source storage area and themigration-destination storage area included in the execution plan tocreate a re-execution plan, wherein, when the migration-source storagearea and the migration-destination storage area are determined to bere-selectable, the microprocessor estimates, on the basis of the historyinformation, a migration completion time required to complete the datamigration from the migration-source storage area to themigration-destination storage area, and wherein, when the estimatedmigration completion time corresponds to a preset prescribed changecondition, the microprocessor changes the migration-destination storagearea to a different storage area included in the storage areas.
 8. Thedata migration management apparatus according to claim 7, wherein themicroprocessor selects, as the different storage area, a storage areahaving either the same or similar attributes as themigration-destination storage area which is a change target.
 9. The datamigration management apparatus according to claim 7, wherein theprescribed change condition is either one or a plurality of: a casewhere the migration completion time estimated this time is a firstprescribed value or longer than a previously estimated migrationcompletion time for the execution plan that failed; a case where thetime required from the start to failure of the execution plan is asecond prescribed value or longer than the previously estimatedmigration completion time for the execution plan; and a case where, whena plurality of data migration pairs configured from the migration-sourcestorage area and the migration-destination storage area are included inthe execution plan, the migration completion time estimated for eitherone of the data migration pairs is a third prescribed value or longerthan the migration completion time estimated for the other datamigration pairs.
 10. The data migration management apparatus accordingto claim 1, wherein a plurality of data migration pairs configured fromthe migration-source storage area and the migration-destination storagearea are included in the execution plan, and wherein the microprocessordetermines that the execution plan failed in a case where a datamigration has failed for either one of the data migration pairs includedin the execution plan, and wherein the microprocessor uses informationthat is used in setting the data migration pair for which the datamigration failed of the respective data migration pairs included in theexecution plan that failed, to create a re-execution plan for completingthe data migration of the data migration pair for which the datamigration failed.
 11. The data migration management apparatus accordingto claim 1, wherein an execution plan management table for storing theexecution plan and the re-execution plan created by the microprocessoris also stored in the memory, and wherein an identifier for identifyingthe execution plan and an identifier for identifying the re-executionplan are set in the execution plan management table so as to differ fromone another.
 12. The data migration management apparatus according toclaim 1, wherein in a case where the re-execution plan has beenassociated with the execution plan that failed, the microprocessorprohibits the creation of another execution plan related to theexecution plan.
 13. An information processing system, comprising: a datamigration management apparatus for managing a data migration; and aplurality of storage controllers, which are connected to the datamigration management apparatus via a communication network, and whicheach has a plurality of storage areas, wherein the data migrationmanagement apparatus has: a memory storing an execution plan formigrating data from a migration-source storage area, which is includedin the respective storage areas, to a migration-destination storagearea, which is included in the respective storage areas; amicroprocessor creating, managing and executing the execution planstored in the memory; and a communication interface for themicroprocessor to communicate via the communication network with thestorage controllers, and wherein the microprocessor migrates the datafrom the migration-source storage area to the migration-destinationstorage area by: (1) creating the execution plan and storing the plan inthe memory; (2) migrating the data from the migration-source storagearea to the migration-destination storage area by issuing an instructionbased on the execution plan to the storage controllers via thecommunication network; (3) determining whether the execution plan wascompleted as planned or failed; (4) using the information included inthe execution plan to create a re-execution plan in a case where theexecution plan is determined to have failed; (5) storing there-execution plan in the memory in association with the execution plan;and (6) issuing a separate instruction based on the re-execution plan tothe storage controllers via the communication network.
 14. Theinformation processing system according to claim 13, wherein historyinformation related to a data migration executed in the past is alsostored in the memory, and wherein the microprocessor estimates amigration completion time required to complete either the execution planor the re-execution plan based on the history information stored in thememory, and outputs the estimated migration completion time inassociation with either the execution plan or the re-execution plan. 15.The information processing system according to claim 13, wherein in acase where the execution plan failed, the microprocessor creates there-execution plan by changing either the migration-source storage areaor the migration-destination storage area, or both, to a differentstorage area in accordance with the reason for the failure.